Temperature effects on electric charge transport processes and electron emission in PBS–clay nanocomposites submitted to electron bombardment

Abstract

Isothermal conditions effects on the charge transport processes and electron emission properties in polybutylene succinate (PBS) nanoclay composites are investigated. The temperature range used (20°C to 80°C) is close to the conditions of use of materials in many applications (insulation, sensors). These effects are highlighted using an appropriate device, placed in a scanning electron microscope (SEM), allowing measurement of induced currents in an electron irradiated specimen. The experimental results showed that the rise in temperature involves a decrease in the charging ability and an increase in conductivity of PBS nanocomposites. The mobility of charge carriers and its thermal dependency deduced during the discharge step were found to be lower for the nanocomposites. A qualitative analysis, expressed for understanding these observations, is based on the determination of electron trap energy distribution (i.e. density of occupied states). Secondary electron emission yield decreased with increasing temperature. The results help us envision a new class of insulators with improved electrical performances. The operating thermal stress, combined with the absence of trapped charges, allows to reduce the electrical and thermal aging and to ensure consequently the long-term reliability of the insulators (for instance under HV).